Powered communications interfaces are utilized in data communications systems to provide operating power to devices over the same wires used to carry data communications signals, in a manner analogous to the traditional telephone system in which DC operating power is provided to subscriber equipment over the twisted-pair telephone wires. Today, there is widespread use of so-called “power over Ethernet” or POE technology, in which DC operating power is provided to digital telephones, video cameras, and other data terminal equipment over unshielded twisted pair (UTP) cables connecting the data equipment with centralized data switches. In POE parlance, a device receiving power in this fashion is termed a “powered device” or PD, while a device that provides power for use by PDs is termed a “power sourcing equipment” or PSE. This method of power delivery is also referred to as “inline power delivery”.